Guys, the seller responded to my question on ebay and said that the year & Omega reference was a typo and that it was also listed on Craig's List.  Still...  Good luck with the bidding, and may the best Club (or Non-Club) Member win!
 
Frank

The optional headphone input could be referring to the fact that older Series basses that are wired stereo can be played through stereo headphones without any other powering unit.  I do it all the time with my '87 Series I